Multi-channel metering devices are used, in particular in the laboratory, for simultaneously metering a plurality of liquid samples. The liquid samples are drawn in from a row of wells of a microtiter plate or other containers in pipette tips releasably attached to the multi-channel metering device or dispensed from the pipette tips into the containers. Multi-channel metering devices have holders with a shank, onto which pipette tips may be clamped. Displacement devices are present for suctioning the liquid samples into the pipette tips and expelling said liquid samples from the pipette tips, and which are able to displace air columns. They are generally designed as a piston-cylinder unit with a cylinder and a piston which is displaceable therein. The displacement devices are connected to apertures in the ends of the shanks via pipes and/or channels and on which the pipette tips are located. After the metering of the liquid samples the pipette tips may be forced off the shanks by means of a throw-off device. Fresh pipette tips may be mounted onto the shanks for further metering. As a result, carry-over between different liquid samples and contamination of the liquid samples and the multi-channel metering device are avoided.
Microtiter plates with 96 wells and a spacing from well to well of 9.0 mm are very common. Microtiter plates with 384 wells and a spacing from well to well of 4.5 mm are also very common. Multi-channel metering devices with rigidly arranged holders can only remove liquid samples from all the wells in a row and dispense liquid samples into said wells with one of the two types of plate. However, multi-channel metering devices are also already known in which the spacings of the holders may be adjusted to the different spacings of the wells. Thus, adjusting the holders by means of a pivotable slide rail for pins fixed to the holders (GB 2 205 400 A), the entire contents of which is hereby incorporated by reference in its entirety, and adjusting the holders via a scissor lever mechanism (EP 0 855 033 B1) the entire contents of which is hereby incorporated by reference in its entirety, are known. The known multi-channel metering devices with adjustable holders are indeed reliable but very costly in terms of construction.
Proceeding therefrom, the object of the invention is to propose a multi-channel metering device with a less costly but nevertheless reliable adjustment of the holders.